The present invention relates to a machine for continuously feeding wire and cutting the wire into preselected lengths for subsequent processing. In general, wire straightening and cutting machines include wire straightening mechanism and feed mechanism for feeding the wire past a wire cutoff and into an elongated wire guide. The cutoff mechanism is actuated to sever the wire when a preselected length is fed into the wire guide and the cutoff guide is opened to laterally discharge the length of wire from the guide. The machines are used to cut wire lengths that vary from a few decimeters to three or more meters. The cycle time of the feeding and cutting machine can be decreased by increasing the speed of wire feed, particularly on long wire lengths. However, increasing the speed of wire feed aggravates the problems encountered in cutting the wire.
Some prior wire straightening and cutoff machines such as disclosed in U.S. Pat. Nos. 1,909,012; 1,982,383; 2,101,860; 2,213,650 and 3,237,829, provide a cutoff mechanism or shear that can move in the direction of the wire feed during cutting. This not only complicates the machine but also introduces some other problems. U.S. Pat. Nos. 1,911,150; 1,925,845 and 3,515,021, provide cutoff mechanisms that are fixed in the direction of wire feed. In such machines, the advance of the wire is interrupted while the cutoff blade moves crosswise of the wire path in a cutting stroke and until the blade has moved clear of the wire path. When the advance of the wire is interrupted by the cutoff mechanism, the rotary wire straightener continues to work the wire while the feed rolls slide relative to the wire and can damage the wire depending on the speed of the wire feed and the interval that the wire advance is interrupted by the cutoff mechanism.
It is desirable to minimize the time that wire advance is interrupted by the cutoff mechanism during a cutoff operation. It is also important that the wire guide be rapidly moved to an open position to discharge the wire after cutting and, that the wire guide be rapidly moved back to a closed condition for guiding the next section of wire, as soon as the wire has been discharged from the guide. In U.S. Pat. No. 3,515,021 a cutter arm 54 is mounted for oscillation with the shaft 41 that operates the movable closure member. The cutter arm and the movable closure member are oscillated in unison by an eccentric driven from a motor through a one-half revolution type indexing clutch mechanism. The wire guide and closure operating shaft must be sufficiently long to accommodate the maximum length of wire being cut, and the closure and closure operating shaft in conjunction with the cutter and eccentric drive, present a high inertia load that is reflected back to the clutch mechanism at the start of each half revolution of the clutch output shaft. High inertia loads can produce rapid wear and/or premature failure of the indexing clutch when operated at high speeds.